Ammonium nitrate explosive



Patented July 8, 1952 lTE 5| AMMONIUM NITRATE EXPLOSIVE James A. Farr, Tamaqua, Pa., assignor to Atlas Powder Company, Wilmington, Del., a corporation of Delaware The present invention relates to explosive compositions. .f

An object of the present invention is the .iprovision of explosive compositionswhich are sufficiently sensitive to detonate-consistently when initiated by a #8 blasting-cap'but which have a relatively low content of ingredients which are per so sensitive to a #8 blasting cap; -1

Another object of -th e invention is the provision of cap sensitive explosive compositions of relatively high density.

A further object of the invention is a provision of cap sensitive explosive compositions of high ammonium nitrate content. f

Still another object of the invention is the provision by relatively safe manufacturing procedure of a capsensitive explosive composition.

Other objects of the invention will be apparent from the following description. 5 v

Ammonium nitrate is capable or exerting poweriu1 explosive force and for many years has been used as an ingredient of explosive compositions. However, because ammonium "nitrate is exceedingly diiiicult to detonate by itself many ammonium nitrate explosives which have been prepared 1 heretofore have contained large amounts of highly sensitive ingredients such as nitro'glycerine, or have been so insensitive that they'have' required special boosters to' initiate .them.

Cap sensitive ammonium nitrate explosives have also been produced by combinations of ammonium nitrate andtrinitrotoluene. Such explosives have, however, usually employed relatively large-quantities of trinitrotoluene, and have usually employed ammonium nitrate in a pulyerized condition of, low density. Ammonium nitrate and trinitrotoluene containing compositions have been prepared by heating trinitrotoluene, or mixtures of trinitrotoluene and other nitroaromatic compounds, to melting tempera- ;tures and agitating with powdered'ammonium nitrate; ,Or, ammonium nitrate and trinitrotoluene have been ground together in wheel mills.

Suchprocedures involving, as they do, heating which-are of relatively high apparent density but which do not contain a high sensitive ingredients.

The explosives of the present'invention are proportion of highly composed of ammonium nitrate of high apparent density as a principal ingredient, a course c'ar 3 Claims. (01. 52--11) 2 bonaceousfuel, and a sensitizer made up of a small proportion of mixed trinitrotoluene and oily dinitrotoluene. Usually, as much as about 90% of the weight of the explosives of the invention may be-taken up by ammonium nitrate, but contents of1am'- monium nitrate as low as about by weight will often besatisfactory. I

One of the advantages of the compositions of the present invention isthatammonium nitrate of highapparent density is used. r

increased.

Usuall satisfactory cap sens ive explosives may be made in accordance with the present invention with ammonium nitrate having an apparent density as high as 1.05. On the other hand the invention is also applicable .to explosives havin ammonium nitrate contents of somewhat lower apparent density. In general it may be saidthat the invention contemplates using ammonium nitrate having an apparentdensity'as low as 0.90. V

The values of apparent density stated in this specification are determined by the cold compression method According to this method, the ammonium nitrate, the density of which is to be determined, at a temperature well below F., is passed through a U. S. S. No. 8 screen to remove any lumps. About milliliters of the ammonium nitrate is then placed in a 300-milliliter cylindrical cup two inches in diameter, and the surface is leveled with a spatula. A plunger 1.81 inches in diameter and actuated by:l6 pounds is lowered into the cylinder until ,it rests on the surface of the ammonium nitrate, and the full weight of 16 pounds is permitted to act for 30 seconds. The plunger i then removed and successively a second and third 100 milliliter portion of ammonium nitrate are added to the cup, and treated in the same manner. The cylinder is then filled to;overfiowing with ammonium nitra'te, andthe weight is againapplied for'30 seconds. 'The ammonium nitrate is struck ofi level with the top of the cylinder, and the contents of the cylinder are weighed. This weight g of ammonium nitrate in grams divided by 300,

and trinitrotoluene, at leastabout 50% ofth'e mixture being trinitrotoluene. Ususallyas much as about 10% of this sensitizer may be used without unduly increasing the amount of sensitive ingredients, and as little sensitizer as is required to include 1% 'dinitrotoluene in the explosive compositions is generally sufiicient.

It is a particular advantage of the present explosives that they do not require the presence of highly sensitive materials such as explosive liquid nitric esters.

carbonaceous fuel, as for example, ivory meal, apricot pit pulp, coarse saw dust, and particularlylcoal, should 'be included in the explosives it also should not be so coarse that it has insufiicient reactivity for proper functioning of the explosive. Usually fuels having a fineness suchthat at least about 99% passes a US. S. No.

'10 screen are not too coarse.

The explosive compositions of the invention may contain other customary dynamite ingredients if desired. Metal nitrates of the type of sodium and potassium nitrate, and finely divided combustible metal powders of the type of powdered aluminum or ferrosilicon,'may be mentioned as exemplary of additional ingredients.

Ammonium nitrate which is used in dynamite compositions is often coated with Waxy materials. Usually it is preferred'tha't'ammonium nitrate employedin the present explosives not be coated.

A particular advantage of the explosives'of the present invention is that they may be produced bysimple mixing at normal room temperatures, that is temperatures between about 65 F. and

abou't'100 F. Also the explosives ofthe present invention may be prepared in standard dynamite mixing machines, and without the use of pulverizing machines or'pulverized ammonium nitrate.

The invention will be further described by the following illustrative examples:

Example 1 85.4 parts by weight of grained ammonium nitrate having an apparent densityof about 0.98 and of a grain sizesuch that about 80% was held on .a U. S. S. No. 100 screen and 80% passed a U. S. S. No. 35 screen was mixed in a dynamite mixer with 6.1 parts by weight of soft coal, all of which passed a U. -S. S. No 10 screen and all of which-was heldona U. S. S. No. 35- screen, and

with 7.0 parts by weight of granular trinitrotoluene. While these ingredients were being mixed, 1.5 parts by weight of oily dinitrotoluene was added and mixing was continued until the ingredients were thoroughly incorporated. The mixing was conducted at room temperature. The

resulting explosive had a density of about 1.09

when packed in 1%" by 8" cartridges. It detonated consistently with a No. 6 blasting cap, and displayed a gap sensitivity of /g".

" Example 2 85.4. parts Weight of grained ammonium nitrate hav'ing'an apparent density of about 1.01

and of a'grain' size such that about passed a U. S. S. No. 35 screen and about 80% was held on a U. S. S. No. 100 screen, 2.5 parts by weight of .crystalline trinitrotoluene, which had been mixed with 1.5 parts by weight of oily dinitrotoluene, 6.1 parts by weight of soft coal, all of which passed a U. S. S. No. 10 screen and all of which was held on a/U. S. S. No. 35 screen, and 4.5 parts by weight of sodium nitrate, all or which passed a U. S. S. No; 14screen and was held on' a US. S. No. 2 5 screen, were mixed together at room temperature'in adynamite mixer. The resulting explosive had afdensity of about 1.07 when packedin' 1 by 8" cartridges, and it detonated consistently with a No. 8 blasting cap.

Example 3 v88 parts by weight of grained ammonium nitrate having an apparent density of about 1.01 and of a grain size .such that 80% passed a U. S S. No.35 screen and 75% was held on a U. S. S. .No 100 screen, 2.5 parts by weight, of crystalline trinitrotoluene which has been mixed With 2.5 parts of oilydinitrotoluene, 7.0 parts by weight of'apricot pit pulp-all of which passed a US. S. No. 14 screen, and all .of which was held on aU. S. S. No. 70 screen, were'mixed together atroomte nperature in a dynamite mixer. The resulting explosive had a density of about 1.10 3321; toggked-intl by 8" cartridges, and it v a consis entl with No. 8 i

What is claimed isz mi can 1. An ammonia dynamite explosive capable o1 detonatmg when initiated with a number 8 blastmg cap and composed of ammonia. dynamite ingredients including ammonium" nitrate, a sensitizer and a carbonaceous fuel, in which the ammonium nitrate has an apparent density above 10% of a mixture of oil'yidinitrotoluene and trinitrotoluene; said trinitrotoluene com risin least about 50% by weight of'said mi ture arf sufiicient ofsaid mixture being present that said explosive contains at least 1% of oily dinitrotoluene; and in which the carbonaceous fuel has a gramsize such that at least about'99% pass'e's a U. S. S. No. 10 screen and nomore passes a U. S. S. No. 100 screen than will provide about of said explosive, said carbonaceous fuel be-- g presen in an amount be 1 I about 12%. I I. i tween about 2% and 2. An explosive according to claim 1 which contains up to about 90% of said ammonium nitrate and in which said, ammonium nitrate has an 'ap:

parent-densitynot greater than; about 1.05.

3. 'An explosive according to claim 2 in which Number the carbonaceous fuel is coal. 995,376 JAMES A. FARR. 1,743,172 1,992,217 REFERENCES CITED 5 2 124 201 lhe following references are of record in the 2,130,712 file of this patent: 2,220,391

UNITED STATES PATENTS Number Sayers June 13, 1911 6 Name Date Sayers June 13, 1911 Ward Jan, 14, 1930 Kirst Feb. 26, 1935 Lewis et a1 July 19, 1938 Cairns Sept. 20, 1938 Cook et a1 Nov. 12, 1940 OTHER REFERENCES Bebie: Manual of Explosives, Military Pyrotechnics and Chemical Agents, published by the MacMiilan 00., New York city (1943). pp. 26 and 

1. AN AMMONIA DYNAMITE EXPLOSIVE CAPABLE OF DETONATING WHEN INITIATED WITH A NUMBER 8 BLASTING CAP AND COMPOSED OF AMMONIA DYNAMITE INGREDIENTS INCLUDING AMMONIUM NITRATE, A SENSITIZER AND A CARBONACEOUS FUEL, IN WHICH THE AMMONIUM NITRATE HAS AN APPARENT DENSITY ABOVE ABOUT 0.90 AND A GRAIN SIZE SUCH THAT AT LEAST 75% PASSES A U. S. S. NO. 35 SCREEN AND AT LEAST ABOUT 15% PASSES A U. S. S. NO. 100 SCREEN, SAID AMMONIUM NITRATE BEING PRESENT IN AN AMOUNT BETWEEN ABOUT 50% AND ABOUT 90%; IN WHICH THE SUBSTANTIALLY SOLE SENSITIZER IS NO MORE THAN ABOUT 10% OF A MIXTURE OF OILY DINITROTOLUENE COMPRISING AT NITROTOLUENE, SAID TRINITROTOLUENE COMPRISING AT LEAST ABOUT 50% BY WEIGHT OF SAID MIXTURE AND SUFFICIENT OF SAID MIXTURE BEING PRESENT THAT SAID EXPLOSIVE CONTAINS AT LEAST 1% OF OILY DINITROTOLUENE; AND IN WHICH THE CARBONACEOUS FUEL HAS A GRAIN SIZE SUCH THAT AT LEAST ABOUT 99% PASSES A U.S.S. NO. 10 SCREEN AND NO MORE PASSES A U.S.S. NO. 100 SCREEN THAN WILL PROVIDE ABOUT 0.1% OF SAID EXPLOSIVE, SID CARBONACEOUS FUEL BE ING PRESENT IN AN AMOUNT BETWEEN ABOUT 2% AND ABOUT 12%. 